1. Field of the Invention
The present invention relates to an auxiliary lock with an adjustable backset. In particular, the present invention relates to a backset-adjustable auxiliary lock that has a simple structure and improved strength.
2. Description of the Related Art
FIG. 10 of the drawings illustrates a conventional auxiliary lock with an adjustable backset. A beveled face 82 on a pushbutton 81 abuts against an underside 84 of an adjusting plate 83 that has a shoulder 85 selectively engaged in one of two notches 87 and 88 of a push plate 86. When adjustment of the backset is required, the pushbutton 81 is pushed to disengage the shoulder 85 of the adjusting plate 83 from, e.g., the notch 87 of the push plate 86 and then engage with the other notch 88 of the push plate 86.
FIG. 11 illustrates another conventional auxiliary lock with an adjustable backset. The auxiliary lock comprises a housing 93 and a casing 92 mounted in the housing 93. The casing 92 and the housing 93 are rotatable relative to each other such that a hook 911 on the housing 93 is releasably engaged in a notch 921 in the casing 92. An L-shaped slot 922 is defined in a periphery of the casing 92, and a key 931 is formed on an outer periphery of the housing 93 and received in the slot 922. The key 931 is slidable along the slot 922 and thus causes a peg 941 on a plate 94 to selectively be engaged in one of two holes 952 and 953 on an extension 951 extending from an end of a deadbolt 95, allowing adjustment of the backset.
However, these conventional auxiliary locks have complicated structures due to numerous parts and thus causes troublesome manufacture. Further, adjustment of the backset is not easy. Further, these conventional auxiliary locks are apt to be destroyed due to insufficient strength.
It is a primary object of the present invention to provide a backset-adjustable auxiliary lock that has a simple, reinforced structure for easy manufacture.
An auxiliary lock in accordance with the present invention comprises:
a housing including a circular hole therein, a faceplate being attached to an end of the housing and including an opening, the housing further including a guide member;
a casing including a first end and a second end, the first end of the casing being received in the housing and including a first positioning slot and a second positioning slot, the second end of the casing including aligned pivot holes, the guide member being selectively engaged in one of the first positioning slot and the second positioning slot, wherein the housing is movable along a longitudinal direction of the housing when the guide member is disengaged from the first and second positioning slots of the casing, and wherein the housing is not movable along the longitudinal direction of the housing when the guide member is engaged in one of the first positioning slot and the second positioning slot;
a deadbolt assembly including a deadbolt, a connecting member, and a pull rod, the deadbolt being received in the housing and slidable between a retracted position in the housing and an extended position in which an end of the deadbolt is beyond the housing, the connecting member being mounted to another end of the deadbolt, the pull rod including a first end mounted in the deadbolt and a second end beyond the deadbolt, the first end of the pull rod including two guide grooves each having a longitudinal section and two retaining sections transverse to the longitudinal section and communicated with the longitudinal section, wherein when the connecting member is in the retaining sections, the deadbolt is not movable along the longitudinal direction of the housing, and wherein when the connecting member is in the longitudinal section, the deadbolt is movable along the longitudinal direction of the housing relative to the pull rod, the deadbolt and the opening of the faceplate being so configured that the deadbolt turns together with the housing when the deadbolt is in its extended position and that the deadbolt is not turnable when the deadbolt is in its retracted position; and
a drive wheel including a cylindrical portion that is rotatably held in the pivot holes of the casing, a drive arm extending from the cylindrical portion and having an end connected to the second end of the pull rod such that rotation of the drive wheel causes movement of the pull rod for moving the deadbolt along the longitudinal direction of the housing.
Other objects, specific advantages, and novel features of the invention will become more apparent from the following detailed description and preferable embodiments when taken in conjunction with the accompanying drawings.